sanchayanmaity/minix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity
minix/servers/mfs/open.c

426 lines
13 KiB
C
Raw Blame History

#include "fs.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include "buf.h"
#include "inode.h"
#include "super.h"
#include <minix/vfsif.h>
PRIVATE char mode_map[] = {R_BIT, W_BIT, R_BIT|W_BIT, 0};
FORWARD _PROTOTYPE( struct inode *new_node, (struct inode *ldirp,
char *string, mode_t bits, zone_t z0, int opaque, char *parsed));
/*===========================================================================*
* fs_open *
*===========================================================================*/
PUBLIC int fs_open()
{
int r, b, exist = TRUE;
struct inode *ldirp;
struct inode *rip;
int oflags;
mode_t omode;
mode_t bits;
char lastc[NAME_MAX];
/* Read request message */
oflags = fs_m_in.REQ_FLAGS;
omode = fs_m_in.REQ_MODE;
caller_uid = fs_m_in.REQ_UID;
caller_gid = fs_m_in.REQ_GID;
/* Device number only for device special files */
fs_m_out.RES_DEV = NO_DEV;
/* Remap the bottom two bits of oflags. */
bits = (mode_t) mode_map[oflags & O_ACCMODE];
/* If O_CREATE is set, try to make the file. */
if (oflags & O_CREAT) {
/* Copy the last component */
err_code = sys_datacopy(FS_PROC_NR, (vir_bytes) fs_m_in.REQ_PATH,
SELF, (vir_bytes) lastc, (phys_bytes) fs_m_in.REQ_PATH_LEN);
if (err_code != OK) return err_code;
/* Get last directory inode */
if ((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
printf("MFS(%d) get_inode for parent dir by creat() failed\n", SELF_E);
return ENOENT;
}
/* Create a new inode by calling new_node(). */
rip = new_node(ldirp, lastc, omode, NO_ZONE, oflags&O_EXCL, NULL);
r = err_code;
if (r == OK) exist = FALSE; /* we just created the file */
else if (r != EEXIST) {
put_inode(ldirp);
return(r); /* other error */
}
else exist = !(oflags & O_EXCL); /* file exists, if the O_EXCL
flag is set this is an error */
}
else {
/* Get file inode. */
if ( (rip = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
printf("MFS(%d) get_inode by open() failed\n", SELF_E);
return ENOENT;
}
ldirp = NIL_INODE;
}
/* Only do the normal open code if we didn't just create the file. */
if (exist) {
/* Check protections. */
if ((r = forbidden(rip, bits)) == OK) {
/* Opening reg. files directories and special files differ. */
switch (rip->i_mode & I_TYPE) {
case I_REGULAR:
/* Truncate regular file if O_TRUNC. */
if (oflags & O_TRUNC) {
if ((r = forbidden(rip, W_BIT)) !=OK) break;
truncate_inode(rip, 0);
wipe_inode(rip);
/* Send the inode from the inode cache to the
* block cache, so it gets written on the next
* cache flush.
*/
rw_inode(rip, WRITING);
}
break;
case I_DIRECTORY:
/* Directories may be read but not written. */
r = (bits & W_BIT ? EISDIR : OK);
break;
case I_CHAR_SPECIAL:
case I_BLOCK_SPECIAL:
/* Send back the device number */
fs_m_out.RES_DEV = (Dev_t) rip->i_zone[0];
break;
case I_NAMED_PIPE:
rip->i_pipe = I_PIPE;
b = (bits & R_BIT ? R_BIT : W_BIT);
if (b == R_BIT)
fs_m_out.RES_POS = rip->i_zone[V2_NR_DZONES+0];
else
fs_m_out.RES_POS = rip->i_zone[V2_NR_DZONES+1];
break;
}
}
}
/* If error, release inode. */
if (r != OK) {
put_inode(ldirp);
put_inode(rip);
return(r);
}
/* Reply message */
fs_m_out.m_source = rip->i_dev; /* filled with FS endpoint by the system */
fs_m_out.RES_INODE_NR = rip->i_num;
fs_m_out.RES_MODE = rip->i_mode;
fs_m_out.RES_FILE_SIZE = rip->i_size;
fs_m_out.RES_INODE_INDEX = (rip - &inode[0]) / sizeof(struct inode);
/* This values are needed for the execution */
fs_m_out.RES_UID = rip->i_uid;
fs_m_out.RES_GID = rip->i_gid;
if ((rip->i_mode & I_TYPE) == I_REGULAR) fs_m_out.RES_CTIME = rip->i_ctime;
/* Drop parent dir */
put_inode(ldirp);
return OK;
}
/*===========================================================================*
* fs_mknod *
*===========================================================================*/
PUBLIC int fs_mknod()
{
struct inode *ip, *ldirp;
char lastc[NAME_MAX];
/* Copy the last component and set up caller's user and group id */
err_code = sys_datacopy(FS_PROC_NR, (vir_bytes) fs_m_in.REQ_PATH, SELF,
(vir_bytes) lastc, (phys_bytes) fs_m_in.REQ_PATH_LEN);
if (err_code != OK) return err_code;
caller_uid = fs_m_in.REQ_UID;
caller_gid = fs_m_in.REQ_GID;
/* Get last directory inode */
if ((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
printf("MFS(%d) get_inode for parent dir by mknod() failed\n", SELF_E);
return ENOENT;
}
/* Try to create the new node */
ip = new_node(ldirp, lastc, fs_m_in.REQ_MODE, (zone_t) fs_m_in.REQ_DEV,
TRUE, NULL);
put_inode(ip);
put_inode(ldirp);
return(err_code);
}
/*===========================================================================*
* fs_mkdir *
*===========================================================================*/
PUBLIC int fs_mkdir()
{
int r1, r2; /* status codes */
ino_t dot, dotdot; /* inode numbers for . and .. */
struct inode *rip, *ldirp;
char lastc[NAME_MAX]; /* last component */
/* Copy the last component and set up caller's user and group id */
err_code = sys_datacopy(FS_PROC_NR, (vir_bytes) fs_m_in.REQ_PATH, SELF,
(vir_bytes) lastc, (phys_bytes)
MIN(fs_m_in.REQ_PATH_LEN, NAME_MAX));
if (err_code != OK) return err_code;
caller_uid = fs_m_in.REQ_UID;
caller_gid = fs_m_in.REQ_GID;
/* Get last directory inode */
if ((ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
printf("MFS(%d) get_inode for parent dir by mkdir() failed\n", SELF_E);
return ENOENT;
}
/* Next make the inode. If that fails, return error code. */
rip = new_node(ldirp, lastc, fs_m_in.REQ_MODE, (zone_t) 0, TRUE, NULL);
if (rip == NIL_INODE || err_code == EEXIST) {
put_inode(rip); /* can't make dir: it already exists */
put_inode(ldirp);
return(err_code);
}
/* Get the inode numbers for . and .. to enter in the directory. */
dotdot = ldirp->i_num; /* parent's inode number */
dot = rip->i_num; /* inode number of the new dir itself */
/* Now make dir entries for . and .. unless the disk is completely full. */
/* Use dot1 and dot2, so the mode of the directory isn't important. */
rip->i_mode = fs_m_in.REQ_MODE; /* set mode */
r1 = search_dir(rip, dot1, &dot, ENTER); /* enter . in the new dir */
r2 = search_dir(rip, dot2, &dotdot, ENTER); /* enter .. in the new dir */
/* If both . and .. were successfully entered, increment the link counts. */
if (r1 == OK && r2 == OK) {
/* Normal case. It was possible to enter . and .. in the new dir. */
rip->i_nlinks++; /* this accounts for . */
ldirp->i_nlinks++; /* this accounts for .. */
ldirp->i_dirt = DIRTY; /* mark parent's inode as dirty */
} else {
/* It was not possible to enter . or .. probably disk was full -
* links counts haven't been touched.
*/
if(search_dir(ldirp, lastc, (ino_t *) 0, DELETE) != OK)
panic(__FILE__, "Dir disappeared ", rip->i_num);
rip->i_nlinks--; /* undo the increment done in new_node() */
}
rip->i_dirt = DIRTY; /* either way, i_nlinks has changed */
put_inode(ldirp); /* return the inode of the parent dir */
put_inode(rip); /* return the inode of the newly made dir */
return(err_code); /* new_node() always sets 'err_code' */
}
/*===========================================================================*
* fs_slink *
*===========================================================================*/
PUBLIC int fs_slink()
{
struct inode *sip; /* inode containing symbolic link */
struct inode *ldirp; /* directory containing link */
register int r; /* error code */
char string[NAME_MAX]; /* last component of the new dir's path name */
struct buf *bp; /* disk buffer for link */
caller_uid = fs_m_in.REQ_UID;
caller_gid = fs_m_in.REQ_GID;
/* Temporarily open the dir. */
if ( (ldirp = get_inode(fs_dev, fs_m_in.REQ_INODE_NR)) == NIL_INODE) {
return(EINVAL);
}
/* Copy the link name's last component */
r = sys_datacopy(FS_PROC_NR, (vir_bytes) fs_m_in.REQ_PATH,
SELF, (vir_bytes) string,
(phys_bytes) fs_m_in.REQ_PATH_LEN);
if (r != OK) return r;
/* Create the inode for the symlink. */
sip = new_node(ldirp, string, (mode_t) (I_SYMBOLIC_LINK | RWX_MODES),
(zone_t) 0, TRUE, NULL);
/* Allocate a disk block for the contents of the symlink.
* Copy contents of symlink (the name pointed to) into first disk block.
*/
if ((r = err_code) == OK) {
r = (bp = new_block(sip, (off_t) 0)) == NIL_BUF ? err_code :
sys_vircopy(fs_m_in.REQ_WHO_E, D, (vir_bytes) fs_m_in.REQ_USER_ADDR,
SELF, D, (vir_bytes) bp->b_data,
(vir_bytes) fs_m_in.REQ_SLENGTH);
if(r == OK) {
bp->b_data[_MIN_BLOCK_SIZE-1] = '\0';
sip->i_size = strlen(bp->b_data);
/*if(sip->i_size != m_in.name1_length-1) {*/
if(sip->i_size != fs_m_in.REQ_SLENGTH) {
/* This can happen if the user provides a buffer
* with a \0 in it. This can cause a lot of trouble
* when the symlink is used later. We could just use
* the strlen() value, but we want to let the user
* know he did something wrong. ENAMETOOLONG doesn't
* exactly describe the error, but there is no
* ENAMETOOWRONG.
*/
r = ENAMETOOLONG;
}
}
put_block(bp, DIRECTORY_BLOCK); /* put_block() accepts NIL_BUF. */
if (r != OK) {
sip->i_nlinks = 0;
if (search_dir(ldirp, string, (ino_t *) 0, DELETE) != OK)
panic(__FILE__, "Symbolic link vanished", NO_NUM);
}
}
/* put_inode() accepts NIL_INODE as a noop, so the below are safe. */
put_inode(sip);
put_inode(ldirp);
return(r);
}
/*===========================================================================*
* new_node *
*===========================================================================*/
PRIVATE struct inode *new_node(struct inode *ldirp,
char *string, mode_t bits, zone_t z0, int opaque, char *parsed)
{
/* New_node() is called by fs_open(), fs_mknod(), and fs_mkdir().
* In all cases it allocates a new inode, makes a directory entry for it in
* the ldirp directory with string name, and initializes it.
* It returns a pointer to the inode if it can do this;
* otherwise it returns NIL_INODE. It always sets 'err_code'
* to an appropriate value (OK or an error code).
*
* The parsed path rest is returned in 'parsed' if parsed is nonzero. It
* has to hold at least NAME_MAX bytes.
*/
register struct inode *rip;
register int r;
/*
*ldirp = parse_path(path, string, opaque ? LAST_DIR : LAST_DIR_EATSYM);
if (*ldirp == NIL_INODE) return(NIL_INODE);
*/
/* Get final component of the path. */
rip = advance(&ldirp, string);
if (S_ISDIR(bits) &&
(ldirp)->i_nlinks >= ((ldirp)->i_sp->s_version == V1 ?
CHAR_MAX : SHRT_MAX)) {
/* New entry is a directory, alas we can't give it a ".." */
put_inode(rip);
err_code = EMLINK;
return(NIL_INODE);
}
if ( rip == NIL_INODE && err_code == ENOENT) {
/* Last path component does not exist. Make new directory entry. */
if ( (rip = alloc_inode((ldirp)->i_dev, bits)) == NIL_INODE) {
/* Can't creat new inode: out of inodes. */
return(NIL_INODE);
}
/* Force inode to the disk before making directory entry to make
* the system more robust in the face of a crash: an inode with
* no directory entry is much better than the opposite.
*/
rip->i_nlinks++;
rip->i_zone[0] = z0; /* major/minor device numbers */
rw_inode(rip, WRITING); /* force inode to disk now */
/* New inode acquired. Try to make directory entry. */
if ((r = search_dir(ldirp, string, &rip->i_num, ENTER)) != OK) {
rip->i_nlinks--; /* pity, have to free disk inode */
rip->i_dirt = DIRTY; /* dirty inodes are written out */
put_inode(rip); /* this call frees the inode */
err_code = r;
return(NIL_INODE);
}
} else {
/* Either last component exists, or there is some problem. */
if (rip != NIL_INODE || err_code == EENTERMOUNT ||
err_code == ELEAVEMOUNT)
r = EEXIST;
else
r = err_code;
}
if(parsed) { /* Give the caller the parsed string if requested. */
strncpy(parsed, string, NAME_MAX-1);
parsed[NAME_MAX-1] = '\0';
}
/* The caller has to return the directory inode (*ldirp). */
err_code = r;
return(rip);
}
/*===========================================================================*
* fs_inhibread *
*===========================================================================*/
PUBLIC int fs_inhibread()
{
struct inode *rip;
if ((rip = find_inode(fs_dev, fs_m_in.REQ_INODE_NR))== NIL_INODE){
printf("FSinhibread: couldn't find inode %d\n", fs_m_in.REQ_INODE_NR);
return EINVAL;
}
/* inhibit read ahead */
rip->i_seek = ISEEK;
return OK;
}
Reference in a new issue View git blame Copy permalink